I agree on that. A power adder can be given to any size engine which means the bigger the engine the more power that it's capable of. However, someone in another post said technology. Of course they went on about power adders, but what about DOHC vs Pushrod.
If both were 350s, which would be capable of pushing out more power? Or is there too many variables?

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91 Z28
Best Time Slip:
60' - 2.098
1/8 - 9.137 , MPH - 76.21
1/4 - 14.213, MPH - 97.55

Mods: SLP Exhaust, umm...nothing else..sorry

Stereo: Alpine 855, Infinity Kappas all around, Infinity 150x2 amp (POS), Infinity Perfect 10 in hatch.

Webpage coming soon.
ICQ: 1437212
AOL: normalmatt9

 

Well if there were a 350 DOHC Chevy,then the DOHC "Should" produce more power because it has more valves per cylinder.But I don't know for sure...Must relate to something else....a ha! The POS Ford Rustang.If you have to time to compare a DOHC V8 mustang verses a pushrod regular, then the DOHC produces more..if the tires don't explod on you.

 

Depends on the power adder... nitrous is easy, it's basically just liquid oxygen, you add the corresponding amount of fuel, you get that much more power. Period. So, you could in theory take a 50 HP engine and bolt a 150 HP shot on it and get 200 HP; or a 600 HP engine and the same 150 HP kit, and you'd get 750 HP. The displacement doesn;t really matter.

Forced induction is a different matter. That acts more like a "power multiplier" than a "power adder". It's easiest to think of it in terms of the air density in the intake: if the forced system doubles the air density, and the coresponding amount of fuel is added, then the engine output is doubled. So with those systems, displacement does matter; of course, the larger the displacement, the larger the "forcer" has to be.

DOHC vs. pushrod is not an issue in either case.

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"So many Mustangs, so little time..."
ICON Motorsports

 

RB83L69,
no no no.... not talking about how a power adder works on them. I'm talking both N/A which is going to be the stronger engine.

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91 Z28
Best Time Slip:
60' - 2.098
1/8 - 9.137 , MPH - 76.21
1/4 - 14.213, MPH - 97.55

Mods: SLP Exhaust, umm...nothing else..sorry

Stereo: Alpine 855, Infinity Kappas all around, Infinity 150x2 amp (POS), Infinity Perfect 10 in hatch.

Webpage coming soon.
ICQ: 1437212
AOL: normalmatt9

 

i think it depends on how far you push technology. Look at the LS1. When GM stopped building the LT5 (DOHC) motor, they said they could get a pushrod engine to get the same output. TA-DA, guess what a 405hp LS6. But, how long did it take, they were making 405hp with 24valves in 92. They are just now there with 12 valves at 2002 (ten years later). Could they have released it sooner? Probably, but not more than about 5 years i bet.
I doubt they would have used titanium in the exhaust in 97.

 

Ions,

I'll hop in here if you and RB don't mind.......

Given both motors are of equal bore and stroke, the DOHC has a better chance of making the most power.

Having said that, you should know that the late, great Smokey Yunick would slap me with his cowboy hat for saying that.

The Smoke Meister did not like DOHC motors, and said many times that 2-valves per cylinder was best.

Well, Smokey was looking at this phenomenon in the late 60's and early 70's, and specifically at Indy motors. He pointed out that 1 large intake valve means fewer transition areas (airflow) to smooth, and also that for simplicity's sake, the 2-valve motors were superior.

Now, having said that, there are some big advantages to 4-valve heads in terms of valvetrain complexity and geometry because they use DOHC. One of them is that the problems of valve-to-rocker arm and rocker arm to pushrod geometry are reduced by elimination of conventional pushrods. 4-valvers get into cam followers and a more direct method of opening the valves. This is one reason you can zing those motors way up into the stratosphere without bending parts.

Also, the total area of 4 small valves within a combustion chamber will almost always be greater than that of 2 valves. This provides an advantage at higher RPM.

Smoke liked the torque from 2-valve Chevy motors best, although I've seen many new designs that have BOTH a torque and HP advantage with 4 valves.

So, why not use 4 valve heads ?

Cost, $$$, Dinero, Sheckels, Drachma, etc.

There is no reasonably priced (under $4,000) 4-valve option in the aftermarket yet - if you include the TOTAL cost associated with them.

For the same $$$ you can throw an ATI supercharger at a motor and blow those 4-valve pretty boy heads back to Japan.

That was Smokey's real argument.

He always thought the Indy boys were Prima Donna's - in fact, when everybody started getting fancy with Novis and Offenhausers, Smoke took an 800 HP Chevy-powered car to Indy and scared the pee-pee out of every team AND the sanctioning body.

He pulled the same stunt at NASCAR (Grand National Stock Car) about every 3 years, just for fun.

And cheat ?

Smoke had 'em all out there dancin' and freakin' out 'cause his stuff was always WAY TOO FAST to be legal - and sometimes they couldn't find out how he was cheating.

One year he showed up with a Chevelle that had a roofline that looked like the outside of a golfball - full of concave indentations like it had been in a hailstorm..........

He said the roof generated less surface/air drag in the wind at high speed. Teams and their managers were screamin' FOUL, FOUL, that's illegal.........

But, hey, there was no rule about that.

In the end, Smokey kept everybody honest. He was a cantankerous old fart from what I hear, but he probably really did have "The Best Damned Garage in Town."

I like guys like that.


BOR

 

So, the DOHC engine is a better engine for making power, allowing it to rev higher which is always a plus. However, the costs to build them is their down side. That's the conclusion then. Right?

Cool story btw

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91 Z28
Best Time Slip:
60' - 2.098
1/8 - 9.137 , MPH - 76.21
1/4 - 14.213, MPH - 97.55

Mods: SLP Exhaust, umm...nothing else..sorry

Stereo: Alpine 855, Infinity Kappas all around, Infinity 150x2 amp (POS), Infinity Perfect 10 in hatch.

Webpage coming soon.
ICQ: 1437212
AOL: normalmatt9

 

One thing left out is that the DOHC intake ports can be larger because there doesn't have to be any room for pushrods. The other advantage of DOHC is that you can design one intake and exhaust combo for low RPM and one for high. That way you get the best of both worlds. There is also the concept of port deactivation where one intake port is closed off forcing all the air through one port which increases air velocity at low RPM. You can also have faster ramp speeds on your cam with OHC with flat tappet(no rollers). The springs are lighter in OHC so valvetrain doesn't wear as much and lasts longer. OHC engines are really wide though, so they're hard to package. I think that's about it.

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'89 Red Formula 350- 350 .060 over forged pistons 232* @ .020 cam Performer RPM Holley 750 DP Vortec 1.94 1.50 Accel Coil and dist. Hedman shorty headers Dual Exhaust w/ cutouts 1LE WS6 suspension, wheels, and brakes, 9 Bolt 3.27 Posi Edelbrock LCA's & Track bar subframe connectors 700R4 Harwood snorkel scoop Eclipse Head Unit Delco Bose Speakers 2 12" Pioneer subs w/ 400 watt/chanel amp

 

Too many variables. Overhead cam engines have a slight advantage over pushrod engines. Then what about single overhead vs. dual overhead camshafts? two valve per cylinder vs. four valve per cylinder? Also you can have four valve per cylinder with a single over head camshaft. All have advantages and disadvantages. Also don't forget cost. The highest naturally aspirated power per cube in drag racing is probably pro stock motorcycle which are now mostly using dohc with 2 valves per cylinder.